With subwoofers bigger is better with regard to longevity. Small subs require huge excursions to do the lowest notes and that requires a lot of power and means there's a lot of pressure in the box. These things both result in higher failure rates than with bigger subs. Velodyne selling 10 inch, sealed subs that play flat to 20 hz is inherently problematic.
I'm not at all bothered by my amp failure. It's 17 years old, that's a pretty long time for electronics.